Free radicals cause problems and can affect the pig's immune system and subsequent performance. Antioxidants can 'mop-up' these free radicals. Thanks to recent research and advancements in nutrition, a finely-tuned 'team' of carefully balanced antioxidants can protect the pig from the damaging effects of free radicals and can help enhance fertility, immunity and growth rates.
By Dr Mike Varley, consultant to SCA NuTec, Dalton, North Yorkshire, UK
The production of free radicals is an inevitable result of biological processes in the body. The vital oxygen molecule (O2) provides the energy for growth, immunity and reproductive processes. These processes involve the oxidation of starch, lipid and even protein into usable glucose as a basic energy source. The O2, or a proportion of it, is rendered down into the sub-units and this leaves the so-called free radicals or individual oxygen atoms with an unpaired electron in either the cells themselves or in the inter cellular spaces.
The more intense the body processes or the higher the metabolic rates, the more free radicals are produced. Fast growing animals, high output sows or highly challenged animals such as the post-weaned piglet will have a high output of free radicals.
Free radicals can be a long lived or a temporary entity in the body, but in both cases they are highly reactive in many biochemical processes. This often means that they can interfere with normal body developments and have a severe negative influence on normal growth and health status. It is well known in humans, for example, that free radicals can interact critically with the DNA structure within the cell nucleus and this can lead to mutations and ultimately cancerous conditions.
Normal growth and health status of finishers can be severely affected by free radicals.
Similarly, if the DNA expression for immune functions or the growth hormone series are affected, then this will inevitably lead to disruption in these processes.
The body has a number of in-built mechanisms to minimise the damage caused by free radicals and to repair any damage that occurs. These include the enzymes superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase.
In addition, antioxidants via the diet play a key role in defending the body against the damaging effects of free radicals and the three key vitamins A, C and E play a vital role here. Polyphenol antioxidants such as those found in plant tissues are also powerful at negating the impact of free radical damage.
There is also good evidence that bilirubin and uric acid can act as antioxidants to help neutralise certain free radicals. Bilirubin comes from the breakdown of red blood cells while uric acid is a breakdown product of purines. Equally too much of these two substances can lead to negative effects, highlighting the need for balance in the supply of antioxidants. Excess bilirubin can lead to jaundice which can eventually damage the central nervous system, while too much uric acid causes gout.
In the light of this it can be seen that there is a constant and active competition going on between free radical production on the one hand and the supply of antioxidants to redress the balance on the other hand.
It is also evident from the above discussion that a supply of antioxidants in the diet can provide a natural boost towards free-radical control. Most pig feeds include vitamin E and vitamin A at variable levels but with more information on the complementary effects of other antioxidants, it is worth considering using more sophisticated blends of antioxidant materials to encourage production processes.
Research has shown the benefits of carefully combining different anti-oxidants. Relying on only one or two routes of antioxidant supply is like putting a football team together with 11 goalkeepers. This team is unbalanced and has no chance of winning.
Far more effective is a combination of different natural antioxidant options that can enhance the body's defence mechanisms and improve production. A combination of vitamin C with vitamin E can provide a platform for this effect. Available forms of the mineral element selenium (Se) in the diet will also interact positively with vitamin functions giving augmented antioxidation.
It is also now well understood that the polyphenol compounds, including the flavonoids and flavones, have powerful antioxidant properties and hence fruit residues and other plant products such as tannins also have a valuable role to play in animal nutrition.
Living proof – PMWS
The advancements in the science of free radicals and antioxidants has been put to good effect in practical pig production systems and an example is in the control of Post-weaning Multi-systemic Wasting Syndrome (PMWS), described as the most difficult disease ever seen in pig production.
New vaccines have made real inroads into the control of the disease but ahead of this has been the important role of boosting immunity by improving all aspects of health and hygiene management. A major contribution towards this can come from anti-oxidants provided through nutrition.
Blends of vitamin E, C, organic selenium coupled with polyphenols and immuno-potentiators such as nucleotides can improve natural immune defence mechanisms in the post-weaned piglet and reduce the worst effects of the disease. They will not cure the disease but will contribute significantly towards the overall level of immune function.
There have been a number of nutritional products developed that are designed to enhance the antioxidation pathways. One of these, developed through Provimi, is Nushield. It combines natural antioxidants and uses vitamins and mineral products blended with natural flavonoid compounds to support every one of the defence routes.
Used to support animal feeding systems where necessary, such as the post-weaned piglet where growth check and health status are always compromised in even the best farming systems, NuShield has been shown to improve feed conversion rates and via this process growth performance.
It has also been used successfully in male and female reproduction support systems. Sperm production in boar studs and oocyte maturation processes in breeding females are all enhanced when an effective programme of antioxidation is used coupled with nutritional excellence.
Antioxidant defence can be compromised as a result of a poor balance between antioxidants and pro-oxidants – that stimulate oxidation. This occurs in high stress conditions and where there is a high disease challenge.
The balance between antioxidants and pro-oxidants in the diet, gastro-intestinal tract, plasma and tissues is an important determinant of health status. Optimal combinations of vitamin E, vitamin C, minerals and natural forms of antioxidant are major players in the maintenance of good health and a high level of performance and reproduction in farm animals. Careful nutritional supplementation can provide significant support to the natural systems to improve animal health and welfare and ultimately performance.
Source: Pig Progress Volume 25 nr 4